Luling Skies Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Luling Skies Observatory clear sky chart from 2005-11-06 to 2025-03-12.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	10% 6% 3 7% 6% 5% 6% 5% 7% 8% 37%	109199
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 45%	109816
Transparency	Day	39% 9% 13% 18% 16% 6%	112908
	Night	34% 7% 14% 19% 18% 8%	114233
Seeing	Day	11% 6% 18% 24% 25% 17%	15027
	Night	12% 5% 18% 31% 27% 8%	24761

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	15% 5% 5% 7% 5% 5% 5% 3 6% 8% 37%	4077
	11th to 20th	Day	13% 8% 2 6% 4 3 3 3 4 5% 48%	4142
	21st to end	Day	20% 8% 3 8% 4 4 5% 4 5% 6% 33%	4972
February	1st to 10th	Day	14% 10% 2 7% 5% 5% 5% 4 5% 7% 37%	2000
	11th to 20th	Day	15% 8% 2 7% 3 3 4 3 5% 8% 42%	1948
	21st to end	Day	16% 8% 3 8% 4 5% 5% 3 5% 8% 36%	1650
March	1st to 10th	Day	19% 10% 3 8% 6% 5% 5% 4 5% 7% 27%	3439
	11th to 20th	Day	13% 6% 3 7% 5% 5% 5% 5% 8% 10% 33%	3491
	21st to end	Day	11% 6% 2 6% 4 5% 5% 4 6% 7% 45%	3973
April	1st to 10th	Day	10% 6% 2 6% 5% 6% 5% 4 6% 8% 42%	2280
	11th to 20th	Day	12% 6% 3 7% 5% 5% 4 4 6% 9% 39%	2254
	21st to end	Day	7% 5% 3 6% 5% 5% 5% 4 6% 8% 47%	2280
May	1st to 10th	Day	8% 5% 2 8% 5% 6% 6% 5% 7% 10% 37%	3765
	11th to 20th	Day	10% 5% 3 7% 5% 5% 5% 4 7% 8% 41%	3764
	21st to end	Day	5% 4 2 6% 6% 6% 6% 5% 7% 10% 44%	4129
June	1st to 10th	Day	9% 6% 3 10% 7% 6% 7% 6% 8% 9% 28%	2280
	11th to 20th	Day	5% 5% 2 8% 8% 7% 9% 6% 9% 12% 28%	2404
	21st to end	Day	6% 7% 3 9% 9% 8% 8% 8% 8% 9% 22%	2470
July	1st to 10th	Day	7% 8% 3 9% 8% 9% 9% 6% 9% 12% 20%	4120
	11th to 20th	Day	6% 6% 3 11% 9% 9% 9% 8% 8% 10% 21%	4034
	21st to end	Day	7% 7% 3 12% 9% 8% 9% 7% 9% 10% 18%	4118
August	1st to 10th	Day	3 3 2 6% 4 5% 6% 5% 9% 11% 44%	3785
	11th to 20th	Day	5% 5% 2 7% 6% 6% 8% 7% 10% 12% 33%	3729
	21st to end	Day	7% 7% 3 12% 8% 6% 6% 5% 7% 7% 30%	4180
September	1st to 10th	Day	12% 7% 3 8% 7% 7% 7% 6% 7% 9% 28%	2280
	11th to 20th	Day	10% 6% 3 8% 6% 6% 6% 5% 7% 9% 34%	2233
	21st to end	Day	8% 4 3 7% 5% 4 6% 4 7% 7% 46%	2090
October	1st to 10th	Day	7% 3 2 6% 4 5% 4 4 6% 7% 52%	1990
	11th to 20th	Day	6% 4 2 6% 4 4 4 3 6% 8% 53%	1900
	21st to end	Day	10% 4 2 5% 3 3 4 3 5% 7% 53%	2090
November	1st to 10th	Day	8% 5% 1 6% 3 4 4 5% 5% 7% 51%	1958
	11th to 20th	Day	10% 7% 2 5% 5% 3 4 2 5% 7% 53%	2000
	21st to end	Day	12% 6% 2 6% 4 4 5% 4 6% 7% 43%	1813
December	1st to 10th	Day	17% 6% 3 6% 4 5% 5% 3 5% 5% 40%	2930
	11th to 20th	Day	9% 6% 2 6% 4 4 4 4 5% 8% 48%	3676
	21st to end	Day	14% 8% 3 7% 4 3 4 3 5% 6% 43%	4955
January	1st to 10th	Night	15% 8% 3 6% 4 4 4 3 4 5% 45%	5868
	11th to 20th	Night	19% 7% 3 5% 3 3 3 2 4 5% 46%	5811
	21st to end	Night	20% 7% 2 5% 4 4 4 3 5% 8% 37%	5984
February	1st to 10th	Night	14% 7% 3 7% 4 4 4 3 6% 6% 42%	2400
	11th to 20th	Night	18% 7% 3 5% 3 3 3 3 5% 7% 43%	2338
	21st to end	Night	17% 7% 3 6% 4 4 4 3 6% 6% 41%	1980
March	1st to 10th	Night	22% 11% 3 8% 5% 4 4 4 5% 6% 31%	3663
	11th to 20th	Night	13% 8% 2 7% 5% 4 5% 4 7% 7% 38%	3497
	21st to end	Night	14% 7% 2 5% 4 4 4 3 5% 7% 45%	3658
April	1st to 10th	Night	13% 6% 2 5% 4 3 5% 4 6% 6% 46%	1900
	11th to 20th	Night	11% 6% 2 6% 4 4 5% 3 5% 7% 46%	1875
	21st to end	Night	5% 4 2 4 4 4 5% 4 6% 8% 54%	1900
May	1st to 10th	Night	13% 5% 3 6% 4 5% 4 4 6% 9% 41%	3130
	11th to 20th	Night	14% 6% 2 7% 4 5% 5% 4 6% 7% 42%	3129
	21st to end	Night	6% 3 1 4 3 4 4 5% 8% 12% 49%	3426
June	1st to 10th	Night	7% 5% 2 5% 4 5% 5% 5% 8% 12% 43%	1900
	11th to 20th	Night	3 5% 1 4 5% 4 5% 5% 9% 12% 47%	1766
	21st to end	Night	6% 5% 2 5% 4 4 4 5% 9% 12% 43%	1710
July	1st to 10th	Night	3 4 2 5% 6% 5% 7% 6% 9% 15% 38%	2850
	11th to 20th	Night	2 2 1 4 4 4 5% 5% 11% 15% 46%	2929
	21st to end	Night	3 4 2 6% 6% 6% 6% 6% 10% 15% 35%	3435
August	1st to 10th	Night	1 2 1 3 3 3 5% 4 8% 12% 58%	3144
	11th to 20th	Night	3 2 1 5% 4 4 6% 6% 10% 15% 44%	3100
	21st to end	Night	4 5% 2 7% 5% 6% 6% 5% 8% 10% 43%	3476
September	1st to 10th	Night	7% 6% 2 5% 5% 6% 6% 5% 8% 10% 39%	1900
	11th to 20th	Night	7% 4 2 6% 5% 5% 6% 5% 7% 10% 43%	1926
	21st to end	Night	8% 4 2 5% 3 4 4 4 6% 9% 53%	2090
October	1st to 10th	Night	6% 4 2 4 4 3 4 3 5% 6% 59%	2185
	11th to 20th	Night	6% 3 2 5% 3 2 4 3 4 7% 61%	2280
	21st to end	Night	10% 4 1 4 4 3 4 3 4 6% 57%	2508
November	1st to 10th	Night	9% 5% 2 5% 3 4 3 3 4 6% 54%	2340
	11th to 20th	Night	12% 5% 1 4 4 3 4 3 5% 6% 54%	2400
	21st to end	Night	10% 6% 2 6% 4 4 4 3 5% 6% 49%	2579
December	1st to 10th	Night	12% 7% 3 8% 5% 5% 4 3 5% 6% 43%	4250
	11th to 20th	Night	9% 6% 2 5% 4 4 4 4 5% 7% 51%	4505
	21st to end	Night	15% 10% 3 7% 3 4 4 2 4 4 44%	5984

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	42% 5% 8% 17% 20% 7%	4078
	11th to 20th	Day	39% 5% 6% 15% 29% 7%	4142
	21st to end	Day	51% 5% 6% 12% 16% 8%	4972
February	1st to 10th	Day	45% 6% 8% 13% 17% 9%	2000
	11th to 20th	Day	40% 6% 9% 17% 18% 8%	1958
	21st to end	Day	46% 6% 10% 14% 17% 6%	1650
March	1st to 10th	Day	53% 7% 10% 15% 11% 4	3439
	11th to 20th	Day	43% 8% 12% 20% 13% 4	3491
	21st to end	Day	35% 8% 12% 16% 21% 9%	3973
April	1st to 10th	Day	36% 9% 14% 16% 17% 9%	2280
	11th to 20th	Day	40% 6% 10% 20% 16% 7%	2254
	21st to end	Day	31% 7% 11% 22% 22% 6%	2280
May	1st to 10th	Day	37% 12% 14% 22% 10% 4	3800
	11th to 20th	Day	37% 8% 11% 20% 21% 3	3768
	21st to end	Day	29% 10% 16% 34% 11% 1	4141
June	1st to 10th	Day	44% 11% 15% 20% 9% 1	2280
	11th to 20th	Day	41% 12% 15% 21% 11% 1	2404
	21st to end	Day	48% 13% 17% 15% 7%	2470
July	1st to 10th	Day	47% 14% 23% 14% 1	4056
	11th to 20th	Day	47% 17% 27% 7% 2	3965
	21st to end	Day	52% 15% 18% 12% 2	3987
August	1st to 10th	Day	27% 9% 17% 26% 21%	3773
	11th to 20th	Day	35% 13% 24% 22% 5% 1	3765
	21st to end	Day	49% 11% 13% 14% 11% 2	4179
September	1st to 10th	Day	46% 12% 17% 12% 10% 3	2280
	11th to 20th	Day	43% 9% 15% 15% 14% 4	2233
	21st to end	Day	35% 8% 12% 21% 15% 9%	2090
October	1st to 10th	Day	28% 4 7% 13% 22% 26%	3302
	11th to 20th	Day	17% 4 7% 21% 28% 23%	3140
	21st to end	Day	20% 5% 8% 12% 41% 14%	3428
November	1st to 10th	Day	30% 5% 9% 23% 25% 8%	1958
	11th to 20th	Day	32% 5% 6% 19% 24% 13%	2000
	21st to end	Day	38% 7% 8% 18% 19% 10%	1813
December	1st to 10th	Day	44% 5% 9% 15% 22% 4	2930
	11th to 20th	Day	33% 7% 9% 21% 22% 8%	3674
	21st to end	Day	41% 7% 7% 15% 25% 4	4955
January	1st to 10th	Night	42% 5% 7% 16% 22% 9%	5868
	11th to 20th	Night	41% 4 5% 16% 26% 8%	5811
	21st to end	Night	45% 5% 9% 14% 17% 10%	5984
February	1st to 10th	Night	42% 5% 8% 17% 19% 9%	2400
	11th to 20th	Night	42% 5% 7% 16% 18% 12%	2339
	21st to end	Night	42% 6% 11% 15% 15% 11%	1980
March	1st to 10th	Night	53% 7% 10% 13% 12% 6%	3663
	11th to 20th	Night	41% 9% 12% 18% 14% 6%	3497
	21st to end	Night	36% 5% 10% 22% 19% 7%	3658
April	1st to 10th	Night	36% 7% 12% 18% 16% 11%	1900
	11th to 20th	Night	37% 6% 11% 21% 17% 9%	1875
	21st to end	Night	27% 5% 11% 25% 25% 6%	1900
May	1st to 10th	Night	36% 10% 14% 23% 13% 4	3160
	11th to 20th	Night	39% 8% 11% 20% 21% 1	3130
	21st to end	Night	23% 9% 19% 34% 13% 1	3435
June	1st to 10th	Night	31% 10% 19% 28% 12%	1900
	11th to 20th	Night	26% 11% 21% 28% 13%	1766
	21st to end	Night	30% 13% 26% 22% 9%	1710
July	1st to 10th	Night	32% 14% 36% 17% 1	2805
	11th to 20th	Night	22% 17% 47% 11% 2	2875
	21st to end	Night	33% 20% 28% 18% 2	3325
August	1st to 10th	Night	16% 9% 25% 31% 19%	3132
	11th to 20th	Night	23% 13% 34% 27% 2	3130
	21st to end	Night	35% 12% 20% 20% 11% 3	3476
September	1st to 10th	Night	35% 12% 22% 16% 12% 3	1900
	11th to 20th	Night	33% 12% 16% 18% 15% 6%	1926
	21st to end	Night	28% 7% 14% 27% 15% 9%	2090
October	1st to 10th	Night	28% 4 8% 14% 22% 23%	3640
	11th to 20th	Night	15% 4 6% 21% 30% 23%	3779
	21st to end	Night	19% 3 7% 11% 41% 19%	4120
November	1st to 10th	Night	31% 6% 7% 22% 24% 10%	2340
	11th to 20th	Night	32% 4 8% 17% 26% 13%	2400
	21st to end	Night	35% 6% 7% 20% 22% 10%	2579
December	1st to 10th	Night	42% 4 7% 19% 21% 6%	4250
	11th to 20th	Night	32% 6% 11% 21% 19% 11%	4506
	21st to end	Night	44% 5% 8% 14% 22% 7%	5984

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 15% 34% 26% 6% 2	300
	11th to 20th	Day	14% 16% 30% 30% 9% 1	300
	21st to end	Day	20% 13% 38% 24% 4 1	330
February	1st to 10th	Day	17% 11% 37% 25% 8% 1	300
	11th to 20th	Day	23% 13% 32% 21% 10% 1	300
	21st to end	Day	11% 16% 43% 21% 8%	249
March	1st to 10th	Day	16% 15% 35% 26% 7% 1	300
	11th to 20th	Day	17% 13% 34% 27% 8% 1	273
	21st to end	Day	14% 8% 33% 31% 11% 2	392
April	1st to 10th	Day	11% 10% 32% 33% 13% 2	460
	11th to 20th	Day	16% 12% 27% 25% 17% 2	452
	21st to end	Day	7% 7% 24% 35% 24% 4	460
May	1st to 10th	Day	8% 6% 22% 32% 26% 6%	463
	11th to 20th	Day	8% 4 18% 31% 29% 10%	487
	21st to end	Day	6% 1 8% 31% 35% 19%	529
June	1st to 10th	Day	9% 2 9% 23% 32% 24%	490
	11th to 20th	Day	8% 2 9% 24% 36% 22%	614
	21st to end	Day	8% 1 8% 24% 32% 27%	680
July	1st to 10th	Day	11% 3 4 17% 33% 33%	671
	11th to 20th	Day	6% 2 4 10% 36% 40%	621
	21st to end	Day	9% 4 13% 32% 42%	532
August	1st to 10th	Day	4 1 3 14% 35% 43%	486
	11th to 20th	Day	9% 1 2 10% 29% 49%	479
	21st to end	Day	9% 3 8% 14% 33% 34%	539
September	1st to 10th	Day	12% 2 6% 16% 36% 29%	490
	11th to 20th	Day	11% 2 8% 20% 36% 22%	490
	21st to end	Day	9% 3 7% 25% 38% 19%	490
October	1st to 10th	Day	6% 2 14% 39% 29% 10%	390
	11th to 20th	Day	6% 4 15% 38% 25% 12%	300
	21st to end	Day	15% 6% 18% 32% 22% 6%	330
November	1st to 10th	Day	12% 4 18% 32% 28% 6%	300
	11th to 20th	Day	17% 7% 27% 28% 17% 4	300
	21st to end	Day	15% 9% 30% 29% 12% 4	300
December	1st to 10th	Day	17% 8% 32% 24% 13% 6%	300
	11th to 20th	Day	15% 11% 35% 32% 7% 1	300
	21st to end	Day	22% 7% 32% 23% 13% 2	330
January	1st to 10th	Night	18% 8% 30% 35% 8% 1	993
	11th to 20th	Night	18% 8% 26% 39% 10%	963
	21st to end	Night	19% 8% 34% 33% 6%	880
February	1st to 10th	Night	17% 7% 30% 37% 8% 1	800
	11th to 20th	Night	21% 9% 29% 31% 10%	783
	21st to end	Night	18% 10% 35% 32% 5%	660
March	1st to 10th	Night	14% 11% 31% 34% 10%	688
	11th to 20th	Night	14% 3 28% 38% 15% 1	575
	21st to end	Night	11% 8% 26% 37% 17%	627
April	1st to 10th	Night	14% 8% 25% 38% 14% 1	570
	11th to 20th	Night	13% 8% 28% 34% 17% 1	563
	21st to end	Night	6% 5% 23% 42% 22% 1	570
May	1st to 10th	Night	8% 3 17% 44% 27% 1	570
	11th to 20th	Night	8% 2 13% 44% 30% 3	561
	21st to end	Night	6% 1 9% 34% 40% 10%	617
June	1st to 10th	Night	8% 2 4 33% 45% 9%	570
	11th to 20th	Night	4 1 5% 23% 53% 14%	570
	21st to end	Night	8% 1 7% 21% 43% 21%	570
July	1st to 10th	Night	6% 1 3 12% 49% 28%	555
	11th to 20th	Night	4 1 1 5% 52% 36%	552
	21st to end	Night	5% 2 13% 50% 29%	624
August	1st to 10th	Night	2 1 12% 49% 36%	567
	11th to 20th	Night	5% 1 2 9% 45% 38%	564
	21st to end	Night	7% 1 5% 15% 45% 27%	627
September	1st to 10th	Night	9% 1 3 17% 47% 23%	570
	11th to 20th	Night	9% 1 5% 23% 49% 14%	596
	21st to end	Night	9% 2 7% 28% 44% 10%	760
October	1st to 10th	Night	7% 1 11% 38% 37% 6%	760
	11th to 20th	Night	7% 4 15% 35% 33% 6%	760
	21st to end	Night	12% 4 19% 36% 27% 3	836
November	1st to 10th	Night	10% 5% 14% 41% 28% 3	780
	11th to 20th	Night	14% 4 20% 39% 21% 2	800
	21st to end	Night	12% 6% 25% 37% 19% 1	800
December	1st to 10th	Night	15% 7% 26% 33% 19% 1	800
	11th to 20th	Night	16% 5% 25% 40% 14% 1	800
	21st to end	Night	21% 9% 26% 33% 11% 1	880

Page generated at 2025-03-09 07:08:42. Version ac07

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